Seal construction for pressure or vacuum chambers

ABSTRACT

Seal construction for use in pressure or vacuum chambers or the like comprising a sealing element which may be selectively placed in sealing position or in a non-sealing position, said sealing element having a working surface adapted to be placed in contact with a wall member and also having a support surface against which biasing means may be selectively urged or relaxed and characterized in that means tending to cause retraction of said sealing element from the sealing position are provided, said retraction means being effective when said biasing means are relaxed.

.[73] Assignee:

United States Patent [191 Grass et al.

[ SEAL CONSTRUCTION FOR PRESSURE OR VACUUM CHAMBERS [751' Inventors: John W. Grass; Gene Roberts, both of Middletown; Glenn V. Williams, Monroe, all of Ohio Diamond International Corporation, New York, NY.

[22] Filed: July 25, 1972 [2 1 Appl No.: 274,990

[111 3,802,961 [451 Apr. 9, 1974 8/1953 Hornbostel 162/371 12/1956 Kelly 162/371 Primary Examiner-S. Leon Bashore Assistant Evaminer-Ri'chard V. Fisher Attorney, Agent, or Firm-Karl W. Flocks [57] ABSTRACT Seal construction for use in pressure or vacuum chamhers or the like comprising a sealing element which may be selectively placed in sealing position or in a non-sealing position, said sealing element having a working surface adapted to be placed in contact with a wall member and also having a support surface I against which biasing means may be selectively urged or relaxed and characterized inthat means tending to cause retraction of said sealing element from the sealing position'are provided, said retraction means being effective when said biasing means are relaxed.

' 16 Claims, 5 Drawing Figures SEAL CONSTRUCTION FOR PRESSURE OR VACUUM CHAMBERS BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to seal construction for forming pressure or vacuum chambers, and in particu lar to an internal seal construction for a vacuum roll.

ing a moving web of paper, metal or other materials;

and picking up web or transferring sheet, an operation required in conjunction with certain printing presses. To produce the vacuum inside the roll, a suitable chamber connected to an external pump or exhauster must be provided, and in order to control the area in which vacuum is applied, as well as to assure optimum operating efficiency of the vacuum system, sealing arrangements must be provided to close off the line of contact between the inside of the rotating, perforated shell of the roll and the internally mounted stationary chamber. Presently a known practice is to mount rectangularly shaped pieces of a non-metallic material having a low coefficient of friction and good wear qualities in a U-shaped member in such a mannerrthat it can be radially forced outwardly against theinternal surface of the rotating shell by springs or an inflatable air pressure tube. Of necessity, operating clearancesmust be provided between the non-metallic sealing element and the channel of the U-shaped holder in which it is disposed. Since in many applications of vacuum rolls, certain parts thereof are exposed to contaminating environments, such as acids, adhesives or the like, and where solid materials can become deposited in the clearances between the seal element and the U-shaped holder, continuous free movement of the seal element becomes very difficult to maintain. Asa result, the seal will become locked in a depressed position corresponding to the least internal radius of the rotating shell, and if there is any eccentricity in the bore of the shell, a clearance will occur when the shell is rotated to any other position and leakage past the seal will occur. In some applications of vacuum rolls, this can cause a fluctuation of the desired internal sub-atmospheric pressure in the roll with consequential adverse effect on the re-- quired function of the roll. Further, continued contact of the sealing element with the roll surface prevents propercleaning thereof and subjects the sealing ele-- ment and/or rotating shell to possible corrosion.

Examples of priorart suction roll sealing assemblies as described hereinabove are disclosed in the following- U.S. Pats. No. 2,578,55l and No. 2,893,487.

SUMMARY OF THE INVENTION Another object of this invention is to provide an internal seal for pressure or vacuum rolls that will at all' times follow and tightly contact the internal surfaces of a rotatable roll shell even though it may have an eccentric or out-of-round bore.

It is still another object of this invention to provide a mounting for the internal seals'of a pressure or vacuum roll which will withdraw the seal from contact with the internal surface of the rotating shell when the roll is not in operation.

It is a further object of thisinven'tion to provide a mounting for the internal seals of a pressure or vacuum roll such that the wearing element can be readily replaced without dismantling the roll assembly.

It is still a further object of this invention to provide a mounting for the internal seals of a pressure or vacuum roll such that the sealing element is in no way restrained by thermal or other forms of expansion in either the seal or the mounting.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a view in perspective of a vacuum roll assembly incorporating the seal arrangement of the present invention; v

FIG. 2 is a sectional view taken along line 22 of FIG. 1 to show details of the sealing arrangement during operation of the roll;

FIG. 3 shows details of the sealing arrangement of FIG. 2 when the roll is in idle condition;

FIG. 4 is a sectional view of the sealing arrangement taken along line 44 of FIG. 2; and

FIG. 5 shows an alternative embodiment similar to FIG. 2, but taken along an upper portion of the vacuum roll so that corresponding members are in inverted order.

DETAILED DESCRIPTION OF THE INVENTION Referring now in detail to the drawings and in particular to FIGS. l4, the novel sealing arrangement according to this invention is seen to be incorporated in a vacuum roll assembly which includes a perforated rotating outer shell 12 and a stationary inner member with edge portion 14. Within the interior of the vacuum roll assembly 10 separate vacuum chambers 16 and 18 may be provided between a plurality of-sealing arrangements 20. I

Each sealing arrangement 20 comprises a longitudinal mounting base 22 and a sealing element 24 adjustably secured thereto. The mounting base 22 is formed with a pair of longitudinally extending, circumferentially spaced apart grooves 21, 23. The sealing element- 24 is also formed with a pair of longitudinally extending, circumferentially spaced grooves 25. Thegrooves 21 and 23 are arranged so as to be oppositely disposed with respect to grooves 27, 25, respectively. Together grooves 21, 27 and 23, 25 form a pair of generally circular channels. Disposed within these channels are circumferentially spaced inflatable tubular members 29 and 31. Sealing element 24 is further formed with a longitudinally extending slot 26 in w hich is disposed an elongated pressure plate or strip of material 28, which may be of metal, for example. The pressure plate or strip 28 is adapted to receive one end of a plurality of I longitudinally spaced pins 30 which are held in place by any convenient means such as spring retaining clips 32,.

ture 34, which has a reduced diameter opening at one end thereof, and extending around each pin is a compression spring 36, one end of which abuts against washer 38 and the other end of which bears against a tapered shoulder around the reduced diameter open- The supporting base 22 further comprises a pair of circumferentially spaced apart, radially inwardly directed shoulders 33, which are held in abutting relationship against the surface of the stationary portion 14. For securing the base 22 to the stationary portion 14, the former is provided with countersunk holes 44 in which the heads 42 of bolts are disposed. In the assembly of the base 22 bolt heads 42 are drawn against shoulders 46 of countersunk bores 44.

A plug member 48 and an air inlet valve arrangement is disposed at opposite ends of each of the tubular members 29, 31. v i For operation of the vacuum roll assembly 10 the sealing arrangement 20 must be inflated to the condicondition of roll assembly 10 the retracting effortof 50 of each tubular member and thus exerting a balanced outwardly directed effort against sealing element When the vacuum roll assembly 10 is to be shut down .to idle condition, the pressure is relieved from the tubular members 29, 31 through valving arrangement 50. As the outward force of the tubular members 29, 31 is dissipated, the retractive effort of spring 36 against washer '38 automatically forces each of the pins 30 radially inwardly of the vacuum roll assembly 10. As each pin 30 is forced radially, inwardly, the force thereof is transferred to pressure plate or strip 28 which conse' quently urges the outer peripheral surface of the sealing element 24 to automatically retract from sealing contact with the inner surface of rotating shell 12 by a distance x, for example. With the sealing elements 24 retracted away from the inner surface of rotating shell 12, the sealing elements 24 will no longer be subject to solidification with the shell 12 and will permit complete washing of the various parts. Thus longer seal life is afforded and high breakaway torque loads are avoided when the vacuum roll is put into operation again.

The alternative embodiment illustrated in FIG. 5 is based upon the same principles of operations as in the -'embodiment of H68. 2-4 and differs therefromin-a number of optional features. In the alternative embodiment of the present invention a sealing arrangement with a' generally steep profile in the radial direction is provided with a mounting base 22' secured to a station ary portion 20' of the vacuum roll assembly. Also, the sealing element 24' is comparatively shortened circumferentially. Base member 22' is formed with elongated grooves 21' and 23' for reception of elongated tubular members 29', 31'. The, sealing element 24' is formed with elongated grooves 27, 25' to receive tubular members 29', 31'. It is also noted that the tubular members 29', 31 are generally elliptical in cross-section instead of circular. The alternative embodiment accord ing to this invention otherwise is similar to the embodiment illustrated in FIGS. 24 in that an elongated slot 26' is provided in sealing element 24'-in which are disposed an elongated pressure plate 28', one end of each pin 30 held in place by a retaining member 32" and in that the pin 30' extends between the inflatable tubular members 29', 31 with a spring 36 therearound in compression relationship with an abutment 38'. Also the abutment 38 may be threaded on pin 30 so that of this invention.

What is claimed is:

1. in a pressure or vacuum roll assembly a sealing arrangement for establishing sealed chambers, said sealing arrangement comprising a base secured to a stationary portion of said assembly, a sealing element mounted on said base and being selectively adjustable to operative'and idle conditions, first means disposed between said base and sealing element for optionally biasing'and maintaining said sealing element in the op erative condition thereof, and second means extending from the base and into said sealing element and contin' uously urging said sealing element to retract toward the idle condition thereof, said second means being of lesser effect than said first means in operative condition but being effective in its retractive effort upon'dissi'pation of the biasing effort of said first means.

2. The sealing arrangement as recited in claim 1 whereinsaid first means comprises at least one inflatable tubular member. I

3. The sealing arrangement as recited in claim 2 wherein said first means further comprises a second inflatable tubular member and being further characterized in that said first and second tubular elements'extend-longitudinally of said roll assembly and generally parallel to each other.

4. The sealing arrangement as recited in claim 3 wherein said base and said sealing element comprise oppositely directed confronting channels in which said first and second inflatable tubular members are disposed.

5. The sealing arrangement as recited in vclaim 4 wherein each of said tubular members includes valve means for inflation or deflation thereof whereby a biasing effort to place said sealing element in an operative condition may be selectively effected or dissipated.

6. The sealing arrangement as recited in claim 5 wherein a pressure plate is disposed in an elongated slot extending longitudinally through said sealing element and said second means extends into said slot and bears against said pressure plate to apply its retractive effort on said sealing element. I

7. The sealing arrangement as recited in claim 6 wherein said second means comprises at least two longitudinally spaced pins extending through said base in a generally radial direction and into the slot of said sealing element.

8. The sealing arrangement as recited in claim 7 wherein said pins extend through generally radial apertures in said base and into said sealing element and a compression spring extends in each of said apertures and around each of said pins and abuts in compression against a shoulder at one end of said apertures.

9. The sealing arrangement as recited in claim 8 wherein one end of each of said compression springs bears against a shoulder portion extending around said reduced diameter opening and the other end of said springs bears against an abutment surface extending around each of said pins at the other end of said springs in compression relationship therewith whereby a retractive effort is exerted against said sealing element.

10. The sealing arrangement as recited in claim 9 wherein said apertures in said base are centrally situated between said tubular members so that a balanced outwardly directed effort may be exerted against said sealing element.

11. The sealing arrangement as recited in claim 10 wherein said vacuum roll includes a rotatable shell with 6 an inner surface against which said sealing element in operation abuts to define separate chambers.

12. The sealing arrangement as recited in claim 11 wherein said tubular members are generally circular in cross-section in their inflated condition.

13. The sealing arrangement as recited inclaim 12 wherein said sealing element and said base are of generally low profile in the radial direction.

14. The sealing arrangement as recitedin claim 11 wherein said tubular members are generally elliptical in cross-section in their inflated condition.

15. The sealing arrangement as recited in claim' 14 wherein said sealing element and-said base are of generally steep profile in the radial direction.

16. The sealing arrangement as recited in claim 11 wherein said abutment surface extending around each of said pins at the other end of said springs is threadedly may be adjusted. 

1. In a pressure or vacuum roll assembly a sealing arrangement for establishing sealed chambers, said sealing arrangement comprising a base secured to a stationary portion of said assembly, a sealing element mounted on said base and being selectively adjustable to operative and idle conditions, first means disposed between said base and sealing element for optionally biasing and maintaining said sealing element in the operative condition thereof, and second means extending from the base and into said sealing element and continuously urging said sealing element to retract toward the idle condition thereof, said second means being of lesser effect than said first means in operative condition but being effective in its retractive effort upon dissipation of the biasing effort of said first means.
 2. The sealing arrangement as recited in claim 1 wherein said first means comprises at least one inflatable tubular member.
 3. The sealing arrangement as recited in claim 2 wherein said first means further comprises a second inflatable tubular member and being further characterized in that said first and second tubular elements extend longitudinally of said roll assembly and generally parallel to each other.
 4. The sealing arrangement as recited in claim 3 wherein said base and said sealing element comprise oppositely directed confronting channels in which said first and second inflatable tubular members are disposed.
 5. The sealing arrangement as recited in claim 4 wherein each of said tubular members includes valve means for inflation or deflation thereof whereby a biasing effort to place said sealing element in an operative condition may be selectively effected or dissipated.
 6. The sealing arrangement as recited in claim 5 wherein a pressure plate is disposed in an elongated slot extending longitudinally through said sealing element and said second means extends into said slot and bears against said pressure plate to apply its retractive effort on said sealing element.
 7. The sealing arrangement as recited in claim 6 wherein said second means comprises at least two longitudinally spaced pins extending through said base in a generally radial direction and into the slot of said sealing element.
 8. The sealing arrangement as recited in claim 7 wherein said pins extend through generally radial apertures in said base and into said sealing element and a compression spring extends in each of said apertures and around each of said pins and abuts in compression against a shoulder at one end of said apertures.
 9. The sealing arrangement as recited in claim 8 wherein one end of each of said compression springs bears against a shoulder portion extending around said reduced diameter opening and the other end of said springs bears against an abutment surface extending around each of said pins at the other end of said springs in compression relationship therewith whereby a retractive effort is exerted against said sealing element.
 10. The sealing arrangement as recited in claim 9 wherein said apertures in said base are centrally situated between said tubular members so that a balanced outwardly directed effort may be exerted against said sealing element.
 11. The sealing arrangement as recited in claim 10 wherein said vacuum roll includes a rotatable shell with an inner surface against which said sealing element in operation abuts to define separate chambers.
 12. The sealing arrangement as recited in claim 11 wherein said tubular members are generally circular in cross-section in their inflated condition.
 13. The sealing arrangement as recited in claim 12 wherein said sealing element and said base are of geNerally low profile in the radial direction.
 14. The sealing arrangement as recited in claim 11 wherein said tubular members are generally elliptical in cross-section in their inflated condition.
 15. The sealing arrangement as recited in claim 14 wherein said sealing element and said base are of generally steep profile in the radial direction.
 16. The sealing arrangement as recited in claim 11 wherein said abutment surface extending around each of said pins at the other end of said springs is threadedly secured on each of said pins whereby the spring force may be adjusted. 